No abstract available

[en] Iron transport in the reticuloendothelial (RE) system plays a central role in iron metabolism, but its regulation has not been characterized physiologically in vivo in humans. In particular, why serum iron is elevated and RE cells are much less iron-loaded than parenchymal cells in idiopathic hemochromatosis is not known. The processing of erythrocyte iron by the RE system was studied after intravenous (IV) injection of 59Fe heat-damaged RBCs (HDRBCs) and 55Fe transferrin in normal subjects and in patients with iron deficiency, idiopathic hemochromatosis, inflammation, marrow aplasia, or hyperplastic erythropoiesis. Early release of 59Fe by the RE system was calculated from the plasma iron turnover and the 59Fe plasma reappearance curve. Late release was calculated from the ratio of 59Fe/55Fe RBC utilization in 2 weeks. The partitioning of iron between the early (release from heme catabolism) and late (release from RE stores) phases depended on the size of RE iron stores, as illustrated by the inverse relationship observed between early release and plasma ferritin (P less than .001). There was a strong correlation between early release and the rate of change of serum iron levels during the first three hours in normal subjects (r = .85, P less than .001). Inflammation produced a blockade of the early release phase, whereas in idiopathic hemochromatosis early release was considerably increased as compared with subjects with similar iron stores. Based on these results, we describe a model of RE iron metabolism in humans. We conclude that the RE system appears to determine the diurnal fluctuations in serum iron levels through variations in the immediate output of heme iron. In idiopathic hemochromatosis, a defect of the RE cell in withholding iron freed from hemoglobin could be responsible for the high serum iron levels and low RE iron stores

[en] Splenic erythropoiesis was demonstrated by surface counting of ⁵⁹Fe in 129 of 1,350 ferrokinetic studies performed over a 15 year period. These 129 studies were carried out in 108 patients, including 40 with chronic myelogenous leukemia (CML), 24 with agnogenic myeloid metaplasia (AMM), 18 with polycythemia vera (PV), six with a myelodysplastic syndrome, five with acute leukemia, three with prostate or breast carcinoma, two each with aplastic anemia or Hodgkin's disease, and one each with idiopathic thrombocythemia, multiple myeloma, chronic renal failure, or treated hypopituitarism. Splenomegaly was present in 83% of the studies and hepatomegaly in 72%. Grade II-III myelofibrosis was demonstrated in 62% of the cases. Hepatic erythropoiesis was present in 77% of the studies (only 38% in PV), and marrow erythropoiesis was undetectable in 33%. Total erythropoiesis was about twice normal (range 0.2 to 8 times normal) but was ineffective to varying degrees in 86% of the studies. Relationships between organomegaly, myelofibrosis, and extramedullary erythropoiesis, as well as differences among clinical disorders, are discussed. Differences observed between CML in chronic or blastic phase suggested that the erythroid cell line was involved in the proliferative process. It is concluded that splenic erythropoiesis (1) is encountered in a variety of clinical conditions; (2) is not necessarily associated with splenomegaly or myelofibrosis, even in the myeloproliferative disorders; (3) is part of a predominantly extramedullary (in the liver as well as in the spleen), expanded, and largely inefficient total erythropoiesis; and (4) can be evaluated in a semiquantitative manner by surface counting

[en] Positron emission tomography (PET) using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) is increasingly used in oncology got the diagnosis and end of treatment evaluation for many tumors. A promising indication for ¹⁸F-FDG PET is the early assessment of response to chemotherapy. The authors reviewed the role of PET in early treatment evaluation of patients with breast cancer. PET is able to predict outcome of neo-adjuvant chemotherapy in most patients. However, our own results in patients with metastatic breast cancer are less optimistic. Further studies are warranted to determine the clinical benefit of early treatment evaluation before using PET routinely in this indication. (author)

[en] Several authors have described the possibility to image intravascular thrombi after injection of In₁₁₁ labelled platelets. Left ventricular thrombi occur frequently in patients with aneurysm; the incidence rate varies from 44 to 78% according to the different authors. This situation represents a model for testing the therapeutic efficacy of anticoagulants or antiaggregants. We studied 13 patients with left ventricular aneurysm. Five patients showed a fixation of labelled platelets 48 or 72 hours after injection. The presence of thrombi was confirmed by echocardiography or ventriculography in all cases. Eight patients were negative at scintigraphy. A thrombus could be identified by other methods in only one case. The incidence of thrombi seems to be higher in patients not receiving anticoagulants. Two patients with a left ventricular thrombus and no treatment were submitted to anticoagulant therapy and retested. The images remain unchanged in one case but in the other, the thrombus was no longer visible. In conclusion, scintigraphy with In₁₁₁ labelled platelets is a valuable method for detecting left ventricular thrombi in aneurysm. It could be a method to appreciate anticoagulant or antiaggregant drug activity. (Author)

[en] Accurate staging of non-Hodgkin's lymphoma (NHL) is important for treatment management. We studied 53 patients (40 patients at initial diagnosis and 13 patients at disease recurrence) with histopathologically proven aggressive NHL to assess the value of whole-body FDG positron emission tomography (PET) as an imaging modality for staging and re-staging NHL. All patients in this comparative analysis were submitted to clinical examination; computed tomography (CT) and whole-body PET studies before starting the treatment. Results: Whole-body FDG-PET seems to be more sensitive than clinical examination and CT imaging for detection of lymph node regions infiltrated by NHL: there were 98 abnormal peripheral lymph node regions seen by FDG-PET: 59 observed by clinical examination and 39 clinically undetected. The clinic examination showed 9 additional nodal lesions not seen by PET. Of 77 thoracic and abdomino-pelvic lymph node regions demonstrated by FDG-PET, 56 lesions were identified by CT while 21 are not illustrated by CT. The CT studies showed 5 additional nodal lesions. Extra-nodal lymphomatous localizations in the liver (n = 5), spleen (n = 14), lungs (n = 8), pleura (n = 9), digestive tract (n = 4), pelvis (n = 2) and other sites (n = 9) were identified by PET. Bone marrow infiltration demonstrated by PET was confirmed by biopsy in 6/10 patients, however known medullary invasion was not seen by PET imaging in 5 patients. Conclusion: whole-body FDG-PET without attenuation correction is an efficient, non-invasive method for staging and re-staging aggressive NHL but marrow biopsy remains to be performed in addition to PET. (author)

[en] 70-80 % of patients with Hodgkin's disease and 50% of patients with non-Hodgkin's lymphoma can be cured. The most appropriate treatment is defined based on histological subtypes, stage of disease and well known risk factors. The authors review the conventional imaging techniques to be performed at diagnosis and the role of positron emission tomography (PET) in this indication. Thereafter, the problem of residual masses is discussed Only those patients in complete remission after the end of treatment have a good chance of long term survival. PET is now the best non-invasive imaging technique for end of treatment evaluation. The potential role of PET for early treatment evaluation and the place of PET during routine follow-up after treatment, as well as the pediatric lymphomas, are also discussed. (author)